Mao Hengfeng, 49, was taken from her home in Shanghai by 30 police officers on 24 February 2011. At first her family believed she had been returned to the labour camp where, until two days earlier, she had been held for nearly a year as punishment for protesting at the trial of Nobel peace laureate Liu Xiaobo. But after almost four months without news, they were finally told that she had been detained at Shanghai City Prison Hospital, though they have not been allowed to visit her yet.

When Hengfeng was previously held at the hospital, in 2008, she was tied to her bed, force-fed and given several injections against her will. While she remains there Amnesty International believes she is at risk of further torture. Her family is deeply worried about her wellbeing.

Since 2004, Hengfeng has been detained and tortured several times because of her work. She has campaigned for women's rights, spoken out on behalf of victims of forced evictions and publicly supported fellow human rights activists.

Hengfeng has also been held at Re-education Through Labour (RTL) facilities, where she has reported that officers there instructed other inmates to beat her. She was hit on the head twice with a chair, leaving a scar over her right eyelid, and was thrown on the floor, causing pain to her lower back, waist and kidneys. She is believed to have been tortured and beaten throughout her detention.

Amnesty International considers Mao Hengfeng a prisoner of conscience, detained solely for exercising her right to freedom of expression, a right which is enshrined in China's constitution.

To email the Mayor of the Shanghai Municipal People's Government and ask him to release Mao Hengfeng, click here